This invention relates generally to an exposure control system for a photographic camera apparatus and, more particularly, to an exposure control system preferably for a fixed focus camera having scanning type shutter blade elements with specially configured primary scene light admitting apertures.
In U.S. Pat. No. 4,104,653, entitled "Scanning Shutter Blade Arrangement with Ambient and Flash Ranges", by B. Johnson et al., issued Aug. 1, 1978, there is disclosed an exposure control for a photographic camera of the type preferably having a fixed focus lens. The exposure control comprises a pair of scanning type shutter blade elements for respectively blocking and unblocking the passage of light through an effective exposure aperture to a film plane and to an effective photocell aperture to a light sensing photocell. The shutter blades include overlapping exposure apertures and photocell apertures and are driven by a rotatable member or walking beam which is controlled to move between first and second arrangements or angular limit positions. As the walking beam is displaced from its first arrangement, the overlapping exposure and photocell apertures of the shutter blades cooperate to establish effective exposure and photocell apertures, respectively, which progressively increase as the walking beam is displaced towards its second arrangement in a well-known manner. A spring bias is adapted to urge the walking beam from its first arrangement toward its second arrangement at the beginning of an exposure cycle. A solenoid is provided to return the walking beam to its first arrangement in respose to a scene light integrating network which determines a point in time in an exposure cycle at which the integral of the light incident on a light sensor exceeds a predetermined value corresponding to a select exposure.
An artificial scene lighted mode of operation is provided during the exposure cycle wherein the flash is fired subsequent to the walking beam moving to its second arrangement in which the shutter blades define the maximum effective exposure aperture. The artificial scene light is provided by a linear flash array which may be removably connected to a complementary socket in the camera housing.
In order to take an ambient scene lighted photograph, the flash array must be removed from the camera. Removal of the flash array from the camera, in turn, operates to position a stop member within the locus of travel of the walking beam to interferingly engage the walking beam at a predetermined intermediate arrangement between the first and second arrangements. Thus, during the ambient scene lighted exposure cycle, the shutter blades move in the aforementioned manner defining ever progressively changing effective exposure apertures until the walking beam is engaged by the stop member to define an intermediate sized effective scene light admitting primary aperture which is less than the maximum sized aperture at which the flash is fired in the aforementioned mode of operation. Since the depth of field increases in correspondence with a decrease in the maximum effective exposure aperture, the aforementioned scanning shutter blade arrangement can provide for an increased depth of field during the predominantly ambient scene lighted mode of operation. Such a system is particularly well suited for use with flash lamps which are removably connected to the camera since the stop member operates as a direct function of the removal of the flash lamp from the camera. However, in camera arrangements which have built-in electronic flash systems which are not detachable from the camera, such stop members cannot be automatically actuated. Thus, some provision would have to be made for the photographer to manually actuate the stop member every time the mode of operation of the camera is changed from an artificial scene lighted mode of operation to an ambient scene lighted mode of operation. However, this additional manual manipulation by the photographer not only detracts from a fully automatic exposure control system, but also, if forgotten, may result in a blurred photograph in the ambient scene lighted mode as a result of the reduced depth of field.
Therefore, it is a primary object of this invention to provide an exposure control system for a photographic camera apparatus of the type having a built-in electronic flash wherein the shutter blade apertures are especially configured to generally provide for a reduced maximum aperture size and a correspondingly increased depth of field during the predominantly ambient scene lighted mode of operation.
It is also an object of this invention to provide an exposure control system for a photographic camera apparatus of the type having a built-in electronic flash wherein the shutter blade elements are especially configured to define a maximum size exposure aperture during the artificial scene lighted mode of operation.
It is an even further object of this invention to provide an exposure control system for a photographic camera apparatus of the type having a built-in strobe and a scanning shutter blade arrangement wherein the blades generally scan to an intermediate sized aperture during the predominantly ambient scene lighted mode of operation and to a maximum sized aperture during the predominantly artificial scene lighted mode of operation without the use of a stop member to inhibit movement of the scanning shutter blades.
Other objects of the invention will be in part obvious and will in part appear hereinafter. The invention accordingly comprises a mechanism and system possessing a construction, combination of elements and arrangement of parts which are exemplified in the following detailed disclosure.